Swingable curtain-type flue damper



2 sheef'sl-sneet 1 Filed Sept. 29, 1944 INVENTOR CHARLES L MYERS TTORNE Y Oct. 18, 1949. C.' L. MYERS 2,485,306

A l 'swINGALE cURTA'IN-'TYPEFLUE DAMPER Filed sept. 29, 1944- 2 sheets-sheet 2 INVENTOR OHHRLES L. MYERS ATTORNEY Patented Oct. 18, 1949 NITED STATES PATENT GFFICE 2,485,306 SWINGABLE. CURTAIN-TYPE- FLUE DAMPER CharlesL. Myers, Philadelphia, Pa.

Application September 29, 1944, Serial No. 556,339

(Cl. .12d-285) 4 Claims. l

This invention relates generally. to dempers for boilers `and the like and more particularly to an improved construction of damper in which is employed -a iiexible curtain adapted to be lpartially or fully applied across the duct in which the damper is installed to control the gas or airow therethrough.

As in the case of the flexible curtainv type damper described in my prior United-Statesv Letters Patent No. 2,349,368, granted May 23, 1944, it is among the principal objects of the present invention to provide an adjustable damper which requires little space for installation, which may be installed in old, as well as new, boiler units with a minimum of structural alteration and expense, and which provides greater capacity -from boilers through conservation and control of the available draft, thereby reducing draft loss and generally increasing the capacity 'and eiiiciency of the boiler unit with which the damper is associated.

More specically, it is `an object ofthe present invention to employ the operating principles of the damper of my prior Patent No. 2,349,368

aforesaid in a simplied and less expensive'conf struction of damper wherein a ilexi'bl-e ycurtain is operatively associated with a swingable supporting frame pivotally mounted in the duct and operative in such manner as to close off, by means of said curtain, all or a portion of the duct tothe flow of gas therethrough.

Other specific objects and advantages of the present invention, as well as economics eii'ected thereby, will be apparent more fully hereinafter, it being understood that the present invention consists substantially in the combination,` construction, locati-on `and relative Iarrangement of parts, all as described in detail hereinafter, as

shown in the accompanying' drawings andas iinally pointed out in the appended claims; In the said accompanying drawings, which areillustrative of preferred embodiments of the principles of the present invention-y Figure l is :a frontY elevational view of a damper constructed and installed in accordance with and embodying the principles of the present invention;

Figure 2 is a rear elevational view thereof;

Figure 3 is `a vertical section-al View taken on the line 3--3 of Figure 1 showing the curtain only partially extended across the duct or flue opening;

Figure 4 is a view similar to Figure 3 but showing the curtain in its fully extended positionto entirely close the flue or duct;

Figure 5 is a vertical sectional viewshowing a somewhat modied installation of the damper of the present invention, the sai-d damper being shown in this ligure in its fully open position;

Figure 6 is a view of the arrangement shownzin in itsfully I0 operatively associated with a swingable frame I I by means of which the curtain is applied wholly lor partially across .a sustaining grille I2 suitably tted within the interior of the duct 43, it being understood, of course, that the damper of the present invention is designed to control the iiow of gases through the said duct I3. The curtain II) is formed of any Isuitable heat and fireresistant material having the requisite flexibility and durability, such as asbestos reinforcedwith metal, or closely woven metal mesh suitably impregnated with `asbestos or the like.l

The frame II, of generally open rectangular form, is preferably constructed of tubular members I4, I5, I6 and I1 suitably secured together, as by welding. Of course, if desired, these frame members may be of any other suitable structural shape. The upper member Ill of the frame II is suitably provided with oppositely directed extensions -I8|8 which respectively project through .opposite w-alls I9-I9. of the duct :and serve to lsupport the frame for swinging movement about the longitudinal axis of said upper member I4 of the frame. As -most clearly appears in Figures 3 and'4, the swinging axis of the frame is disposed immediately adjacent one wallvof the duct, for example, the back wall 2U, so that when said frame is swung `from its dotted line position yshown inFi'gure 4 into its full line position, the bottom edge I6 of the frame is immediately adjacent the opposite wall ofY the duct, in this case, the front wall 2| thereof. Inasmuch as the frame [I is of a Width closely approximating the internal lwidth. of the duct as measured from side wall to sidewall thereof, it will be apparent that when the frame is swung into the ,position shown in Figure 4, the -several frame members I4, I5', I6 .and IT are. respectively disposed in close relation to the internal surfaces of the several walls' of the duct.

The liexible curtain II) is of a width approximately equal to that ofthe duct, `its Opposite free edges being close to, if not in actual engagement, with the internal surfaces of the duct side 'walls f I 9-I9'. The upper edge of the curtain is iixedlY secured, as at. 22, tothe back wall 2l) of the duct immediately above the upper member Ill of the swingable trame Il, while the lower edge. ofthe curtainis suitably secured, as -at 23, to the lower member' IG of,v the frame.

It will be noted-that the curtain I is of a length somewhat greater than the corresponding overall dimension of the frame so as to provide the curtain with a `certain amount of slack, the purpose of which will presently appear.

Mounted within the duct I3 is the sustaining grille I2 consisting generally of an open rectangular frame formed of an upper member 24, side members 25-25 and a bottom member 26, all of which members are suitably secured, as by welding, bolting or otherwise, to each other and to the corresponding side walls of the duct. This grille is disposed in an inclined lplane as shown most clearly in Figures 3 and 4, the upper member 24 being secured to the duct wall irnmediately above the swinging axis of the frame I I, the upper edge of the flexible curtain I0 being clamped between the duct wall and said upper member 24 of the grille.

The bottom member 2B of the sustaining grille is provided with an angularly bent portionv 2'I disposed in the general plane of the grille, the free edge of said `portion 21 being notched, as at 28, at spaced intervals to form a plurality of ports, #preferably of V-shape, for more closely and accurately controlling the gas flow through the duct when the damper curtain immediately approaches or recedes from its fully closed position shown in Figure 4. The side members 25- 25 of the grille are each provided with flanges 29 Which freely extend inwardly from the opposite walls of the duct and lie in the general plane of the grille to serve as contacting surfaces for the opposite edges of that portion of the curtain which is in operative engagement with the sustaining grille.

Preferably, the grille I2 is additionally provided with a plurality of laterally spaced grille rods 3U the opposite ends of which are suitably secured, as by welding, to the upper and lower member 24 and 26 of the grille. In order to provide the grille with capacity for expansion and contraction due to temperature variations to which it may be subjected, these grille rods 30 may be provided intermediate their opposite secured ends with expansion joints on the order of that shown in Figure 7 wherein it will be observed that each grille rod is formed of two sections 3| and 32, the section 3I being provided with a thimble 33 for reception of the free proxr imate end of the section 32, the latter being thus axially movable within the thimble to compensate y In Figures 5 and 6, the construction of the duct is modied somewhat to provide the back wall thereof with a rearwardly offset section 35 within which may be accommodated the swingably mounted frame II, thereby providing the duct with a flow passage for the gas of maximum area when the damper is fully opened. Also, the modication of Figures 5 and 6 illustrates the use of an operating lever 36, in lieu oi the sprocket-andlchain device, for oscillating the swingable frame II of the damper, it being understood that such operating lever may be substituted for the sprocket-and-chain shown in connection with the damper arrangement of Figures 1 to 4 inclusive.

In the operation of the damper as hereinbefore described, it will be apparent that for full opening of the duct I3 to gas ilow therethrough the frame II is swung away from the grille I2 and into the dotted line position shown in Figure 4 or into the full line position shown in Figure 5. In such position of the frame II, the curtain Ill will depend free of the grille, thereby entirely exposing the latter to the ilow of gas freely throughout the entire extent of the grille, the draft now being in the direction as indicated by the arrows in Figures 3, 4 and I5. In such case, of course, the duct I3 is fully open to the passage of the gases therethrough.

When, however, it is desired to reduce the draft passage throughthe duct, the frame II is swung about its pivotal axis so as to reduce the subtended angle between said frame and the grille I2, the degree of this angle determining the extent to which the curtain I 0 overlies the grille I2. For example, when the frame I I is positioned as shown in Figure 3, the curtain I0 is caused, by the pressure of the gas flowing upwardly through the duct, to press against the Igrille I2 in the upper region 40 thereof in consequence of which the draft flow is only through that portion 4I of the grille which remains uncovered by the curtain. Due to the fact that the opposite side edges of the curtain are pressed against the side anges 29-29 of the grille in said closed-off region 40, the portion of the curtain which is thus pressed against the grille effectively interrupts and reduces the flow of gas (or air) through the duct. As the frame II is swimg toward the grille I2 an increasingly greater portion of the latter is sealed 01T against the now of gas therethrough by the curtain, and conversely, as the frame II is swung out of its fully closed `position shown in Figure 4 away from the said grille, the curtain is gradually peeled away from the grille to provide a ilue passage of gradually increasing area.

It is important to note at this point that the operation is such that there is no frictional resistance to overcome between the grille I2 and the curtain IIJ, the effective portion of the latter being merely pressed against or peeled away from the grille as the frame I I is swung about its axis in one direction or the other. In certain instances, the grille may be entirely dispensed with, in which case the curtain per se may be suitably reinforced, as by the use of transversely extending stiffening rods arranged in spaced parallel relation, so that it is self-sustaining when positioned to partially or wholly close oi the duct to the flow of gas (or air) therethrough.

In order to more accurately control the draft ow characteristic and to insure a ilow of controlled minimum value when the curtain is all but fully closed, the bottom member of the grille is V-ported as previously described. The V-ports 28 are so disposed that as the lower portion of the curtain is pressed against the plate 2l by the action of the draft through the duct, during the last stage of the damper-closing movement of the frame II, free communication between the upstream and downstream sections of the duct is progressively and gradually decreased to zero value. Conversely, as the damper commences to move to open position from its fully closed position, these V-ports 28 aiord increasingly large openings between the closed-off-sections of the duct, thereby providing a gradually increasing S and accuratey controlled minimum flow to suit almost any requirement for and condition of boiler operation.

By the use of a duplex arrangement of the damper embodying the principles of the present invention, as by employing a pair of curtains in conjunction with a swingable frame disposed therebetween with the upper edges of the curtains commonly fixed to the wall of the flue and the lower edges correspondingly secured to the lower free edge of the frame, the pair of curtains may be selectively employed to control the draft flow through one or the other of a pair of ducts extending angularly with respect to each other, each of these ducts being provided with its own sustaining grille for one of the damper curtains. In such an arrangement, the duplex damper may serve as a "splitter damper to control the ilow of gases (or air) through the two ducts, part of the ow being through one duct and part through the other It will be understood, of course, that the present invention may be modified in other respects than as indicated hereinbefore and may be employed in installations other than as described all without departing from the real spirit or general principles thereof. For example, the damper of the present construction is adapted for use and may be installed in the ducts of air-conditioning systems not only to regulate and control the flow of air therethrough and so improve the efficiency of operation of the system, but also to close off the duct in which it is installed in the event of re, thus precluding the possibility of the duct serving as a conduit for fire. In fact, the damper of the present invention maybe employed in any system wherein it is desired to accurately control or completely and effectively interrupt the flow of gas or air through a conduit. Accordingly, it is intended to claim the present invention broadly, as well as specifically, as indicated by the appended calms.

What is claimed as new and useful is:

1. A damper for controlling the draft through a flue comprising, in combination, a curtain of flexible material adapted to be adjustably eX- tended across the flue opening to close off more or less of the latter, one edge of said curtain being secured across substantially the full width of one wall of the ue opening, the opposite edge of said curtain being shiftable laterally away from said wall across the full extent of said flue opening, a sustaining grille for the curtain disposed within and extending transversely across the full extent of the flue opening with one edge thereof secured to the aforesaid wall of the flue immediately adjacent the secured edge of the curtain, and means operatively associated with the curtain for swinging the shiftable edge thereof along an arc intersecting the plane of said grille whereby to apply a greater r lesser portion of the curtain against the upstream of said grille, said last-mentioned means being in the form of a frame swingable about an axis closely adjoining and paralleling the secured edge of said curtain and said curtain being disposed in overlying relation with respect to said frame for swinging movement therewith toward and away from said gril e.

2. A damper for controlling the draft through a ue comprising, in combination, a flexible curtain of a width adapted to iit snugly between the opposite side walls of the flue and adapted to be adjustably extended laterally across the full eX..

tent of the flue opening to close off more or less of the latter, one edge of the curtain being secured to one of the iiue walls intermediate said side walls so that the main body of the curtain depends freely from said secured edge, a sustaining grille for the curtain extending transversely of the flue opening and the freely depending main body of the curtain, and a swingably mounted frame operatively associated with said curtain to angularly adjust the position of the latter with respect to said sustaining grille, said frame being swingable about an axis closely adjacent to and paralleling the secured edge of the curtain and the opposite edge of said curtain being secured to the .corresponding free edge of said swingably mounted frame, the curtain being disposed in overlying relation with respect to said frame for swinging movement therewith toward and away from said grille, said curtain being of a length sufficiently greater than the corresponding length of the frame to provide it with suflicient slack to completely cover the upstream side of the grille when said frame is swung to the limit of its permissible movement transversely across the flue opening.

3. A damper for controlling the draft through a flue comprising, in combination, a fixed grille disposed within and extending transversely of the ue opening, a flexible curtain of a width adapted to t snugly between the opposite side Walls of the ue for adjustable application over the upstream side of said grille, one edge of said curtain being secured to one of the flue walls intermediate said side walls so that the main body of the curtain depends freely from said secured edge and transversely of said grille, and a supporting frame for the curtain operatively associated therewith for gradually applying an increasing portion of the curtain over the upstream side of the grille, the said gradual application of the curtain to the grille being initiated from the secured edge of the curtain while the opposite edge thereof traverses an arc intersecting the plane of said grille, said frame being swingable about an axis closely adjacent to and paralleling the secured edge of the curtain and said curtain being loosely extended across the full length of the frame for' swingable movement therewith toward and away from said grille.

4. In a damper as defined in claim 2 wherein said grille includes a bale member having V- shaped ports in one edge thereof which is adapted to be overlapped by the outer slack portion of thecurtain as the latter approaches or is withdrawn from its fully extended condition with respect to the grille.

CHARLES L. MYERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 19,203 Osgood Jan. 26, 1858 932,172 Porter Aug. 24, 1909 1,138,994 Steele May 11, 1915 2,349,368 Myers May 23, 1944 FOREIGN PATENTS Number Country Date 1,040 Great Britain Mar. 10, 1880 '76,229 France Apr. 27, 1867 

